From 6c0309402f761a8f704e53b44a124e23f636c509 Mon Sep 17 00:00:00 2001
From: Olivier Prat <olivier@zvork.fr>
Date: Tue, 11 Sep 2018 16:14:54 +0200
Subject: [PATCH] Some fixes for HBAO. Need performance improvements

---
 .../render-utils/src/AmbientOcclusionEffect.cpp     |  7 +++++--
 libraries/render-utils/src/ssao.slh                 | 13 +++++++++----
 libraries/render-utils/src/ssao_makeOcclusion.slf   |  4 +---
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/libraries/render-utils/src/AmbientOcclusionEffect.cpp b/libraries/render-utils/src/AmbientOcclusionEffect.cpp
index 12b8c62556..0cc5220abf 100644
--- a/libraries/render-utils/src/AmbientOcclusionEffect.cpp
+++ b/libraries/render-utils/src/AmbientOcclusionEffect.cpp
@@ -184,12 +184,15 @@ void AmbientOcclusionEffect::configure(const Config& config) {
         auto& current = _parametersBuffer.edit().radiusInfo;
         current.x = radius;
         current.y = radius * radius;
-        current.z = (float)(1.0 / pow((double)radius, RADIUS_POWER));
+        current.z = 10.0f;
+#if !SSAO_USE_HORIZON_BASED
+        current.z *= (float)(1.0 / pow((double)radius, RADIUS_POWER));
+#endif
     }
 
     if (config.obscuranceLevel != _parametersBuffer->getObscuranceLevel()) {
         auto& current = _parametersBuffer.edit().radiusInfo;
-        current.w = config.obscuranceLevel * 10.0;
+        current.w = config.obscuranceLevel;
     }
 
     if (config.falloffBias != _parametersBuffer->getFalloffBias()) {
diff --git a/libraries/render-utils/src/ssao.slh b/libraries/render-utils/src/ssao.slh
index 8e1cb27346..b4dd7e6b6c 100644
--- a/libraries/render-utils/src/ssao.slh
+++ b/libraries/render-utils/src/ssao.slh
@@ -305,8 +305,11 @@ float evalVisibilitySSAO(in vec3 centerPosition, in vec3 centerNormal, in vec3 t
             vec3 tapUVZ = fetchTap(side, centerPixelPos, tap, imageSize);
             vec3 tapPositionES = evalEyePositionFromZeye(side.x, tapUVZ.z, tapUVZ.xy);
             vec3 deltaVec = normalize(tapPositionES - fragPositionES);
+            float rawHorizon = dot(deltaVec, fragNormalES);
 
-            <$horizon$> = max(<$horizon$>, dot(deltaVec, fragNormalES));
+            rawHorizon *= 1.0 - radius / ssDiskRadius;
+
+            <$horizon$> = max(<$horizon$>, rawHorizon);
         }
     }
 <@endfunc@>
@@ -368,7 +371,8 @@ vec2 searchHorizons(ivec4 side, ivec2 centerPixelPos, vec2 imageSize, vec2 delta
 
     // Forward search for h1
     vec2 clampedSearchVec = clampSearchVec(imageSize, vec2(centerPixelPos), searchVec);
-    int stepCount = int(floor(length(clampedSearchVec)+0.5));
+    vec2 absClampedSearchVec = abs(clampedSearchVec);
+    int stepCount = int(max(absClampedSearchVec.x, absClampedSearchVec.y));
     if (stepCount>0) {
         vec2 deltaPixelTap = clampedSearchVec / float(stepCount);
         float deltaRadius = length(deltaPixelTap);
@@ -376,7 +380,8 @@ vec2 searchHorizons(ivec4 side, ivec2 centerPixelPos, vec2 imageSize, vec2 delta
     }
     // Backward search for h2
     clampedSearchVec = clampSearchVec(imageSize, vec2(centerPixelPos), -searchVec);
-    stepCount = int(floor(length(clampedSearchVec)+0.5));
+    absClampedSearchVec = abs(clampedSearchVec);
+    stepCount = int(max(absClampedSearchVec.x, absClampedSearchVec.y));
     if (stepCount>0) {
         vec2 deltaPixelTap = clampedSearchVec / float(stepCount);
         float deltaRadius = length(deltaPixelTap);
@@ -411,7 +416,7 @@ vec2 searchHorizons(ivec4 side, ivec2 centerPixelPos, vec2 imageSize, vec2 delta
 float evalVisibilityHBAO(ivec4 side, ivec2 centerPixelPos, vec2 imageSize, vec2 deltaTap, float ssDiskRadius, 
                          vec3 fragPositionES, vec3 fragNormalES) {
 	vec2 horizons = searchHorizons(side, centerPixelPos, imageSize, deltaTap, ssDiskRadius, fragPositionES, fragNormalES);
-	return (horizons.x + horizons.y) * 0.5;
+	return (horizons.x + horizons.y) * 0.5 / PI;
 }
 
 <@endfunc@>
diff --git a/libraries/render-utils/src/ssao_makeOcclusion.slf b/libraries/render-utils/src/ssao_makeOcclusion.slf
index 89f2aadfab..e2c8a5ffa6 100644
--- a/libraries/render-utils/src/ssao_makeOcclusion.slf
+++ b/libraries/render-utils/src/ssao_makeOcclusion.slf
@@ -46,9 +46,7 @@ void main(void) {
 
     // Choose the screen-space sample radius
     float ssDiskRadius = evalDiskRadius(fragPositionES.z, imageSize);
-#if SSAO_USE_HORIZON_BASED
-	ssDiskRadius = min(ssDiskRadius, 3.0);
-#endif
+
     // Let's make noise 
     float randomPatternRotationAngle = getAngleDithering(centerPixelPos);